In recent years, some cell phones and mobile terminal devices have been configured so that light is emitted from a light-emitting member such as a light emitting diode (LED) installed in a housing when a face panel is touched by a user's finger, pen, or the like. In this kind of the mobile terminal device, for example, an electrostatic sensor is installed in the housing and detects a change in electrostatic capacity to make the light-emitting member emit light when the face panel is touched. Thus, the mobile terminal device may realize various light-emitting modes depending on manners of touching a face panel. A user may enjoy various illuminations realized by the mobile terminal device.
Exemplary mobile terminal devices are disclosed in Japanese Laid-open Patent Publication Nos. 2008-131597, 2009-99067, and 2007-311044.
However, the aforementioned conventional mobile terminal device has a problem in that the sensitivity of the electrostatic sensor is low. This problem will be described with reference to FIG. 7. FIG. 7 is a diagram illustrating an internal structure of the conventional mobile terminal device. As illustrated in FIG. 7, the mobile terminal device 90 includes a face panel 91 to be touched by a user. The mobile terminal device 90 includes a flexible printed circuit board 92, electrostatic sensors 93a and 93b, a LED 94, and spacers 95a and 95b in housing. The electrostatic sensors 93a and 93b and the LED 94 are connected to the flexible printed circuit board 92. The spacers 95a and 95b are placed in the housing to avoid formation of unnecessary spaces in the housing.
When a user's finger, a pen, or the like touches the face panel 91, the electrostatic sensors 93a and 93b, which are formed in the vicinity of the position where the finger or the like is touched, detect a change in electrostatic capacity. The LED 94 emits light when the electrostatic sensors 93a and 93b located near the LED 94 detect a change in electrostatic capacity.
As illustrated in FIG. 7, the distance from the face panel 91 to the electrostatic sensors 93a and 93b is long. Thus, the electrostatic sensors 93a and 93b may be difficult to detect a change in electrostatic capacity even when the finger or the like touches the face panel 91. The mobile terminal device 90 may cause a decrease in sensitivity of the electrostatic sensors 93a and 93b due to the internal structure of the mobile terminal device 90. The emission of light from the LED 94, which is interlocked with detection by the electrostatic sensors 93a and 93b, may be effectively represented in a preferable manner.